Thermostat



THERMOSTAT Filed Dec. 23, 1936 u a w r F L 0 m a 5 mh% a 1 M 1 Z I ma/F/ H .H 9 f ii N g m mtornqyxi Patented May 13, 1941 THERMOSTAT HaroldB. Drapeau, Chicago, IlL, assignor to The Dole Valve Company, Chicago,Ill., a corporation of Illinois Application December 23, 1936, SerialNo. 117,348 4 Claims. (Cl. 291-15) The invention has as a further objectto provide a thermostat which is used to do work and which is soconstructed that the amount of work which can be done by the thermostat,having any given amount of thermostatic metal, is in- V creased. Theinvention has as a further object the changing of the distribution ofthe metal of the bimetal element about a given plane, to increase itscapacity to do work. The invention has as a further object to sodistribute the metal of the bimetal element about its axis, that is aline running longitudinally through the longitudinal center plane of themetal, so as to increase the moment of inertia, thereby reducing theamount of the bimetal required to accomplished any given result.

In the manufacture of v bimetal for thermostatic uses, the rolling millpractice does not permit the rolling of this metal to uniform thicknessthroughout its length, so that there is a variation in the thickness ofthe bimetal at different points along its length. This variation inthickness may range from five to ten percent of the total thickness ofthe strip. These strips of thermostatic bimetal, therefore, as now made,do not have a uniform rigidity. One of the objects of the presentinvention is to provide a thermostatic bimetal strip which will maintaina higher uniformity of rigidity.

The invention has further objects which are more particularly pointedout in the accompanying description.

Referring now to the drawing, Fig. 1 is a sectional view through oneform of thermostatic device embodying the invention; 7

Fig. 2 is a view of Fig. 1 taken at right angles thereto;

Fig. 3 is a view showing the thermostatic device as used in connectionwith the cooling system of an automotive vehicle;

Fig. 4 is an enlarged view of a portion of the thermostatic bimetal, inpart section;

Fig. 5 is a sectional view taken on line 5-5 of Fig. 4;

Fig. 6 is a view of a modified construction where the thermostaticdevice is used in connection with an electric circuit;

Fig. 7 is a view showing a modified construction.

Like numerals refer to like parts throughout the several figures.

In the drawing I have set out certain forms and uses of the thermostat,but it is of course evident that the invention may be embodied in anyother suitable form and may be given any other desired use. I have alsoillustrated several different forms of the strip of thermostaticbimetal, deformed in different ways to increase the magnitude of itsmoment of inertia, thereby increasing the work a given amount ofthermostatic metal can do, or decreasing the amount of thermostaticmetal required to do any given amount of work, and have simplyillustrated sev-' eral different way of deforming the metal, but it isof course evident that it may be deformed in various other ways withoutdeparting from the spirit of the invention.

Referring to the construction illustrated in Figs. 1 to 5, there isshown one form of device particularly adapted to be used in connectionwith the cooling system of an internal combustion engine as used inautomotive vehicles. In this construction there is a casing l which haspivotally mounted therein a valve 2 which,-when in its closed position,closes the passageway through the casing, the valve being pivoted at 3.A strip of thermostatic metal l has one end 5 connected with the valve 2in any desired manner, so as to move this valve ,to its open positionwhen the temperature of the cooling liquid rises above a predeterminedpoint. This connection between the strip of thermostatic metal and thevalve is shown as being made by the link 6 which is pivoted at 1 to theend of the thermostatic strip and at 8 to the valve. In this particularconstruction, the -valve is provided with a housing 9 for this pivot.The casing i is provided with the laterally extending wall In. In thisconstruction the thermostatic strip is formed in a coil and the other"end is connected with a fixed part Illa which is supported by theprojecting arms llib, connected with the casing I.

In Fig. 3 the casing I is shown as being located in the circulatorycooling system of an internal combustion engine Ii. In this view thewall I0 is clamped between the member I! and the part I! of the engine.Connected with the member I! is a pipe H which connects with theradiator IS. The pipe i4 is preferably made in two sections connectedtogether by the connecting member it, which may be a hose section.

The thermostatic strip is made up of two pieces of metal l1 and i8 ofany of the usual metals used for this purpose, such as a ferrous and anon-ferrous metal. The bimetal strip is deformed to provide a' rib I9extending longitudl.. nally therealong, preferably near the middlethereof. This rib may be formed in any desired manner, but I prefer toform it with curved faces. One of the simplest ways of forming it is tobend the trip intermediate its edges so that bent portions projectbeyond the face of the adjacent portions thereof. When this is donethere is provided a groove l9a on one side of the metal and a rib on theother side.

I have found that this rib maintains a higher uniformity of rigidityalong the length of the strip when there are variations in the thicknessof the strip, as occurs in the usual method of manufacturing the strip.This construction also permits a lesser amount of thermostatic metal tobe used to secure any given result. This construction also provides athermostat wherein the amount of work that can be done by thethermostat, having any given amount of thermostatic metal, is increased.In Fig. 1, for example, the thermostatic device is shown as connectedwith a valve in the circulatory system of an internal combustion engine.For a quick warm-up, it is essential that the rigidity of thethermostatic coll be sufilcient to hold the valve in the heaton positionduring the warm-up period. This construction permits this to be donewith much less metal than with the ordinary fiat'bimetal elements. .1

In Fig. 6 there is illustrated a construction where the strip ofthermostatic metal 4 is conriected at one end to a fixed part 20 and isprovided with a contact member 2| which works between the electriccontacts 22 and 23 which are connected by the wires 24 and 25 in anysuitable circuit, so that the thermostat is used to make and break thecircuit.

This construction not only provides a thermo-' static strip having ahigher uniformity of rigidity along its entire length, but it reducesthe cost of the thermostat by reducing the amount of bimetal necessaryto secure a given result.

In Figs. 4 and I have illustrated a simple and effective means ofdeforming a strip of bimetal so as to increase the magnitude of itsmoment of inertia. It is of course evident that this strip may bedeformed in various. other ways to secure this result, so as to therebyincrease the amount of work any" given amount of thermostatic metal canaccomplish, or reduce the amount of thermostatic metal required for anygiven purpose.

In Fig. 7 there is illustrated a modified construction wherein the twometal elements I! and I8 of the bimetal are left in their original formand there is attached to one of them, extending longitudinallytherealong, a metal member 28 which may be brazed, soldered or otherwisefastened in position. I I

I claim:

1. A bimetal thermostatic element to be used in a thermostatic device,comprising two pieces of metal, having different coefiicients ofexpansion, connected together; and provided with a longitudinallyextending rib, said rib formed by bending a portion of both of thebimetal strips between their edges so as to cause the metal of one pieceto'project into the plane of the main body portion of the other piece.-

2. A. bimetal thermostatic element to be used in a thermostatic device,comprising two pieces of metal, having different coefllcients ofexpansion, connected together, and a longitudinally extending rib oneach of said pieces, said rib having a curved outer face.

3. A bimetal thermostatic element to be used in a thermostatic device,comprising two pieces of metaLhaving different-coefficients ofexpansion, connected together, a projecting rib on one side thereof, andan opposed groove on the' other side thereof, the projecting rib formedon one of the pieces of the bimetal element and the groove formed in theother bimetal element.

4. A bimetal thermostatic element to be used in a thermostatic device,comprising two pieces of metal, having different coefficients ofexpansion, connected together to form a strip, the strip made up of thetwo pieces being deformed near its middle, whereby a more uniformrigidity of the strip is secured.

HAROLD B. DRAPEAU.

